Chainsaw Repair

The pump was not intended to pump raw fuel into the engine. The pump merely draws fuel through the carburetor and back to the tank so the carburetor can function normally as intended.

If the 455 floods as a result of working the pump bulb, then there is a problem with the needle and seat of the metering valve (leaking) inside the carburetor.

The carbs have a pump on one side and a demand regulator on the other.

The pump keeps fuel in the metering chamber of the carb and the regulator lets fuel into the carburetor venturi as manifold vacuum increases from the engine turning over faster.

The pump is run by the impulse line.

455 is one of the easiest/reliable starting saws I've ever seen. Like has been said, the saw cannot be flooded with the primer bulb.

Question 1: How many times does he pull the rope with the choke on? Over-choking is the most common way to flood a saw. I'm guessing he's missing the initial "pop" and continuing to pull with the choke on. This is pretty common.

Question 2: Was this saw set up and adjusted at time of purchase? Too lean on the lo adjustment makes for a harder starting saw. Another indication here would be real boggy acceleration on start up unti, warm.

Question 3: Does the primer bulb firm up/fill up after 3-4 pumps? If it stays empty the carb is probably junk. But this issue is generally found on a saw that constantly stalls, so if the saw runs OK once started, then don;t worry about this one.